Many of the early concepts for monitoring the lead/device electrical signals of a pulse generator device failed due to complexity, potential sealing problems or due to size constraints. Currently, monitoring of lead/device electrical signals is achieved by one of two methods.
The first method requires hex shaped drivers to be inserted through seal plugs into a hexagon shaped opening of a set screw of a pulse generator device. The hexagon shaped driver is then electrically connected to various external equipment via an alligator clip/wire attached to a metal shaft of the hexagon shaped driver.
The disadvantages of such an approach are:
1. Poor electrical contact made between hex driver and set screw head.
2. Plurality of alligator clips causes both confusion on diagnostic end of cables and possibility of shorts between the tightly spaced alligator clips on limited space of the shaft of the hexagon shaped driver.
3. Method is extremely cumbersome.
4. Damage to seal plugs is dependent on the number of insertions. Each extra insertion to test the device reduces the reliability of the seal.
5. If all the ports of the device need to be monitored at the same time, the physician must have multiple set screws, clips, and cable arrangements on hand.
6. The time required to make electrical contact to the device is lengthy thereby increasing the time the wound is exposed which increases patient risk and the possibility of infection.
7. High voltage signals sent through poor contacts may be shunted, resulting in reduced defibrillation energy being delivered to the heart.
8. Movement of the cable causes noise spikes in electrical contacts.
In the second method, electrical contact to the pulse generator device is made in essentially the same way and the same problems persist. By this method, opposed clamps are inserted into opposed sealed plugs. The opposed clamps are tensioned towards each other by rubber bands which force contact of the clamps into the diagnostic blocks after passing through seals. The inward force on the opposed clamps causes a loosening of the clamps. Slight movements of the cable show up as noise spikes on the supporting diagnostic equipment. Although this is an improvement over the first method approach, the same problems remain.